During the time that liquid fuel is not dispensed from an underground tank, leakage can be detected by observing changes in the liquid top surface level in the tank. However, if liquid fuel is being intermittently dispensed from the tank, as via a pump and metering means, it is clear that changes in top surface level liquid fuel in the tank do not per se reflect leakage. There is need for accurate, reliable and simple means to monitor both liquid level in the tank as well as the amount of liquid dispensed from the tank for supply to multiple dispensers in order to arrive at an accurate determination of any such "unwanted loss". The latter can arise for example from drainage through small holes in the tank, or from pilferage from the tank, as via an inlet to the tank or leakage from hoses or lines leading from the tank to the dispenser.
There is also need for equipment to accurately monitor and report, for predetermined recording periods, gross and net fuel volumes, average fuel temperature in the tank, volumes of fuel deliveries received in the tank; and volume of fuel dispensed, as via the multiple dispensers.